Transdermal products can and will crystallize from time to time. That shouldn't be an issue. I would put the bottle in a deep plate with hot water, let the bottle sit in the water for ~10 minutes and then shake the bottle well a see, if the solid piece diffuses.
I've had some transdermal products, that I've had to do this before every application, but for some products only one time has been enough (and no need to do this for most products, of course). Worst case scenario though, you only miss a bit of the product, if the warming up and shaking doesn't diffuse the piece. Rest of the product is still good for use.